Drying means for offset rotary printing machine



P. DlETRlCH 2,768,576

DRYING MEANS FOR OFFSET ROTARY PRINTING MACHINE,

' Oct. 30, 1956 Filed June 21. 1952 INVENTOR n m m Mm R A m, D L w PM BUnited States Patent DRYING MEANS FOR OFFSET ROTARY PRINTING MACHINEPaul Dietrich, Augsburg, Germany, assignor to MaschinenfabrikAugsburg-Nurnberg A. G., Augsburg, Germany, a corporation of GermanyApplication June 21, 195.2, Serial No. 294,874 Claims priority,application Germany July 20, 1951 3 Claims. (Cl. 101177) This inventionrelates to an offset rotary printing press, more particularly formulti-color printing.

It is an object of the present invention to improve presses of thisclass so as to achieve a quality of printing which is equal, or evensuperior, to that of web fed rotogravure printing or sheet fed offsetprinting presses.

A special object of the invention consists in the provision of meanspreventing the colors inadvertently mixing with each other on the paperand/ or repelling each other upon mixing while wet on the paper.

. Another object of the invention is to provide means for obtaining ,OIlweb fed offset multicolor presses clear and beautiful tints and coloreffects of sufficient depth, similar to that which can easily beobtained by offset sheet fedprinting presses or rotogravure printingpresses.

- Still another object, of the invention is to provide means forensuring accurate register and a ready and convenient accessibility ofthe inking units.

With these and further objects in View, the present invention-the inkingand printing devices are arranged in such a way that not more than twoprinting with their plate and rubber offset cylinders) operate inconjunction with a common large impression cylinder. A drying device forthe printed ink is arranged over the circumferential surface of thelarge impression cylinder and immediately following each rubber offsetcylinder or printing station. Thus, the fresh ink printed on the paperweb is dried immediately after each printing operation and before theprinted web reaches the next offset cylinder or printing station so thatthe wet ink applied by the next impression will be applied to a driedweb having the same physical condition as before the first printingimpression rather than to a paper web carrying a wet ink impression.Blending and mutual repelling of the wet applied colors on the paper webis thus rendered impossible. Also, the printing on one side dried andthus prevented from dabbing on the next impression cylinder duringimmediately subsequent printing on the reverse side of the Web, and theprinted impressions are prevented from smearing during passage of theprinted web through subsequent paper guiding and folding devices.

The invention will be better understood by reference to the followingdetailed description in connection with the accompanying drawing showingby way of example and purely diagrammatically a multi-color offset webfed roto-gravure printing press having the invention applied thereto.

Referring to the drawing, it will be seen that the web 2 of paper,cloth, or any other material is passed to the first impression cylinderthrough a per se known tensioning device 3 and guide rollers 4. Theimpression cylinder 5 cooperates with two rubber offset cylinders 6 and7 with each of which is associated a plate cylinder 8 and 9,respectively, having corresponding inking and dampening devices 20, 21and 22, 23, respectively. It is well understood that the inksconventionally used for offset printing are substantially higher boilingor less volatile according to i or impression stations (including inkingdevices together c 2,768,576 Patented Oct. 30, .1956

than some letterpress inks, and are not susceptible to quick rapid flashdrying at temperatures sufliciently low as not to damage the paper.Arranged over the surface of the impression cylinder and between therubber offset cylinders 6 and 7 are hoods 10 and 11, said hoods beinglocated over the circumferential surface of the impression cylinder 5 soas to cover the printed surface of web 2 for a substantial timefollowing each of the printing impressions received thereon fromcylinders 6 and 7, cylinder 5 being of the order of four times as largeas cylinder 6 or 7 as shown in the drawing. Hoods 10 and 11 areconstructed as drying devices adapted to such a substantial part of thecircumference of the impression cylinder, or the printed impressions onthe web covering that sector of the impression cylinder 5 to a dryingaction of sufficient intensity and duration to effect drying of theprinted impression prior to contact with the next printing station orrubber offset cylinder. In this way sufficient time and path of travelis provided over the extended surface of the impression cylinder to drythe higher boiling offset type of ink at a temperature below thatwhichwould damage the paper. t

On leaving the impression cylinder 5 the web 2 is passed over guiderollers 12 to the next impression cylinder 13 on which, for instance,printing on reverse side of web 2 is achieved at the two printingstations associated with impression cylinder 12. (including two rubbercylinders 14 and 15 and plate cylinders 16 and 17, respectively,together with the associated inking and dampening devices 24, 25, and26, 27, respectively). Here again, associated with impression cylinder13, are drying hoodslS and 19 arranged to subject the impressions on web2 to drying following each rubber cylinder 14 or 15.

The web may then be further handled in any desired manner. Thus, one ormore additional impression cylinders may follow, for instance, if theprinting on web 2 is to include more than two colors. Also the web maybe passed directly to conventional cutting and folding apparatus (notshown), or a wind-up device of conventional construction (not shown) mayfollow. Of course, the printing on the first side of web 2 may beaccomplished with more than two colors, by including an additionalimpression cylinder with not more than two printing stations andassociated drying hoods, and/or providing suitable means forturning theweb by perse known turning bars between the first and the secondimpression cylinders for printing additional impressions on either side.

It will be understood that the construction of the printing pressaccording to the present invention not only has the advantage of asimple and clear arrangement of the machine in the so-called tandemarrangement, but it also ensures accurate register and ready andconvenient accessibility of the inking units.

Hence it is not necessary to arrange the inking devices so as to beremovable.

While the invention has been described in detail with respect to a nowpreferred example and embodiment of the invention it will be understoodby those skilled in the art after understanding the invention thatvarious changes and modifications may be made without departing from thespirit and scope of the invention and it is intended, therefore, tocover all such changes and modifications in the appended claims.

What is claimed is:

1. In a multicolor web fed offset rotary printing press of the characterdescribed having a plurality of offset printing stations adapted tosupply sequential impressions of high boiling offset inks to a web ofpaper, the combination which comprises :an impression cylinder for eachtwo of said offset printing stations, an offset roll at each of saidprinting stations for transferring an impression of said high boilingoffset ink to said paper web against said impression cylinder, said inkimpression requiring a predetermined substantial time for the dryingthereof at a temperature less than that which will damage said paperweb, means for mounting two of said printing station offset rollsadjacent said impression cylinder at substantially diametricallyopposite sides thereof for sequential printing contact with paper onsaid cylinder, the circumferential extent of said impression cylinderbetween said two offset rolls being substantially twice thecircumference of said rolls, a pair of arcuate hoods between saidprinting stations and overlying substantially the entire portions of thesurface of said impression cylinder between said offset rolls, and meansfor supplying a drying medium through said hoods to the surface of saidpaper on said impression cylinder for drying each ink impression appliedthereto at a temperature less than will damage said paper web and priorto the application to said paper of a subsequent ink impression at asubsequent oifset roll.

2. In a multicolor offset rotary printing press of the characterdescribed having a plurality of printing stations for applyingsequential impressions of off-set high boiling ink to a paper web, thecombination which comprises an impression cylinder for each two of saidprinting stations, an offset roll in each of said printing stations fortransferring an impression of said offset ink to said paper web againstsaid impression cylinder, said ink impression requiring a substantialtime for drying at a temperature less than will damage said paper weband the diameter of said impression cylinder being approximately fourtimes that of each said offset ro ll providing said substantial dryingtime for each said ink impression, means for mounting said offset rollsadjacent said impression cylinder at substan tially diametricallyopposite sides thereof for sequential printing contact with paper onsaid impression cylinder, and means overlying substantially the entiresurface portions of said impression cylinder between said olfset rollsfor drying said ink impression applied to the paper at a temperatureless than will damage said paper prior to the application of asubsequent ink impression by a subsequent offset roll.

3. In a multicolor offset rotary printing press having an impressioncylinder and a plurality of offset'printing stations each including anoffset roll for applying sequential impressions of offset ink to a paperweb against said impression cylinder, saif offset ink impressionsrequiring a substantial time and length of travel for drying at atemperature less than will damage said paper web, the combination whichcomprises means for mounting not more than two of said printing stationsassociated with said impression cylindensaid stations being mounted atdiametrically opposite sides of said cylinder for sequential printingcontact with said paper :and the diameter of said impression cylinderbeing approximately four times the diameter of said oifset rollsproviding said substantial References Cited in the file of this patentUNITED STATES PATENTS 1,504,409 Yetter et al. Aug. 12, 1924 1,724,644 DeLong Aug. 13, 1929 2,000,684 Allen et a1. May 7, 1935 2,103,812Ericksson Dec. 28, 1937 2,202,134 Barber May 28, 1940 2,499,870 LuehrsMar. 7, 1950 FOREIGN PATENTS 189,035 Germany Dec. 19, 1906 556,841France July 27, 1923

